The objective of this project is to establish the potential role of the oligosaccharide moieties of glycoproteins as information-bearing macromolecules able to direct specific activities of glycoproteins by interaction with oligosaccharide receptors. The approach will be to demonstrate that significant differences in oligosaccharide structure exist among closely related glycoproteins and that these differences can be distinguished by hepatocyte receptors. Carbohydrate moieties from two groups of glycoproteins will be sequenced. One group, immunoglobulins, will include a rat IgE, human IgD, J-chain and secretory component. The other group will consist of serum glycoproteins, ceruloplasmin and heptoglobin, synthesized by hepatocytes and which appear to bear oligosaccharides with unique structures. By establishing these structures the specificity and diversity of the synthetic systems of single cell types can be assessed. In addition, similarities and differences in oligosaccharide structure and location along both homologous and non-homologous polypeptides can be identified. These defined oligosaccharides will then be utilized in binding studies with hepatocyte receptors designed to demonstrate the basis of their specificity.